It's a sport where some competitors fall from cliffs, dislocate fingers, crack ribs, run from wild pigs, deprive themselves of sleep, consume strange foods, develop blisters, and most importantly have a ton of fun.

In the 100-mile race, competitors run a 20-mile loop starting at the Hawai'i Nature Center and navigate a series of trails through Tantalus, Manoa, Nu'uanu and back. Competitors must complete five loops on the obstacle-filled course.

"It reminds me of being a little kid again, jumping over rocks and trees, and getting dirty," said competitor Bob McAllaster of Kailua. "It's just a lot of fun."

McAllaster was one of 88 starters in the endurance run considered by organizers and competitors as one of the hardest courses in the world because of the terrain, humidity and more than 23,000 feet of vertical climb. Of the 88 starters, 17 completed the 100-mile course, and 52 completed the optional 62.5-mile course earlier this month.

This year's winner, James Gifford of Washington, completed the 100-mile race in 27 hours and 25 minutes.

Competitors are equipped with headlamps and flashlights, and run all day and night. Many of the elite runners stop briefly at the course's 15 aid stations to gather water and food, and continue running again.

"I try to get in and out in under a minute because the clock is going," said four-time women's champion Monica Scholz of Canada, who finished 100 miles in 31:35. "I get tired if I slow down. You don't get tired if you keep your heart rate going."

Marty Fritzhand, of Cincinnati, does not sleep a wink when he competes. Fritzhand, a 61-year-old surgeon, completed the 62.5-mile course in 31:05.

McAllaster and runners in HURT simulate race conditions by training at the Hawai'i Nature Center on Fridays after work. McAllaster finished the 62.5-mile course in 23:53.

"We'll meet here at 5 or 6 p.m. and train all night," said McAllaster, a 46-year-old business consultant. "We'll do 40 miles and go to the next day  to Saturday. That's pretty good sleep deprivation training."

Many runners suffer from blisters because of the wet conditions, and improper socks and shoes, according to Command Sgt. Maj. Joel R. Jenkins, who assists at the race.

"We teach them how to take care of their feet," said Jenkins, who works at the Tripler Army Medical Center. "Believe it or not, we talk to them while we're fixing their feet. When your feet hurt, the rest of your body doesn't want to follow."

IT CAN REALLY HURT

Furthermore, competitors must get adequate hydration and nutrition on the course. Each competitor burns about 18,000 to 20,000 calories in the event, but the majority of them gain weight because they're ingesting so much fluid from aid stations, Jenkins said.

"That's a good sign," Jenkins said. "Some people sit down and have potato soup because it's a high glycemic index food and it's absorbed easily. Whatever works for them."

John Salmonson, the founder and president of HURT, recalled numerous extraordinary events at the recently completed endurance run.

One of the competitors, Mike Sweeney of California, was taken to the Queen's Medical Center after he "fell off a cliff" and broke his finger, Salmonson said.

"He convinced the doctor to snap the finger back and give him a shot of painkiller," Salmonson said. "He came back on the course and finished the 100 kilometer (62.5 miles)."

Another competitor fell on the first lap and "broke two ribs," Salmonson said. The man, who works as a United Airlines pilot, developed "real serious blisters," but still completed the 62.5-mile course with cracked ribs, Salmonson said.

"He couldn't hardly breathe, but he held his posture upright and was able to somehow do it coming up and down these mountains," Salmonson said.

CLOSE ENCOUNTERS

And not to be outdone, two competitors from Iowa and Virginia got personal with "a 400-pound pig" coming down the trail at them in the middle of the night, Salmonson said. "It's quite an adventure."

Scholz, 37, said the key to the race is to keep moving. Scholz, who works as an attorney, holds the world record for most 100-mile completed races in a calendar year with 23.

"Beware of the chair," said Scholz, who has completed 70 or 80 100-mile races since taking up running in 1996. "You're not making relentless forward progress sitting in the chair. Don't spend time in the aid station. A lot of people will spend a half hour in the aid station, and they'll run out of time. Especially on this course because it's a tight time."